Method and apparatus for aeroponic farming

ABSTRACT

A system and method of aeroponic farming includes depositing seeds in a flat containing micro-fleece cloth and placing the flat within a growth chamber. The upper side of the flat is subjected to light of the proper frequencies to promote growth in plants. A nutrient solution is sprayed onto the micro-fleece cloth and the developing root mass of the plants, while controlling temperature, humidity, and carbon dioxide within the growth chamber. The plants are harvested resulting from the seeds at a desired stage of growth. The growth chambers can be stacked on each other and/or located side by side to save space within a facility, and to permit sharing the subsystems which control the nutrient solution, temperature, humidity, and carbon dioxide for the growth chambers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser.No. 60/608,687 filed on Sep. 10, 2004 and entitled METHOD AND APPARATUSFOR AEROPONIC FARMING, incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to the field of aeroponics, and moreparticularly to an apparatus which enhances the efficiency of aeroponicfarming.

BACKGROUND OF THE INVENTION

Aeroponic growing is distinct from other hydroponic or soil-less plantculture which include ebb and flow, pond, and aggregate growing methods.In the ebb and flow method, the roots are periodically submersed inliquid nutrients; in the pond culture method, the roots are suspended ina solution of liquid nutrients, which solution is generally oxygenated;and in the aggregate growing method, the liquid nutrients are suppliedto plants in a non-soil containing aggregate. Because plants requireoxygen to their roots, hydroponic methods are designed to allow bothoxygen and liquid nutrient to sustain the plants. Aeroponics sprays theliquid containing nutrient solution on the plant roots. These roots aregenerally bare and suspended in the chamber where the nutrients aresprayed.

“Hydroponics” began in the 1850's, was commercialized in the 1920's, andused by the Army in WWII. It includes using water, sand, and aggregatecultures as the growth medium. Plants fully immersed in water grow lesswell due to lack of oxygen for their roots. Methods to supplement oxygento roots include providing an intermittent flow of nutrient solution tosupply the plants (NFT, or “Nutrient Film Technology”), aerating thenutrient solution, and spraying of nutrients on roots. The second issimilar to the joint Cornell University, NYSEG (New York State Electric& Gas), and NYSERDA (NYS Energy Research and Development Authority)facility where ponds have oxygen injected into the nutrient solution.Some researchers at Cornell have sprayed roots with nutrient solutions.Visits to several facilities identified the drawbacks of NFT and pondsystems, such as the large amounts of water required, the need forsophisticated light control and cooling systems, insect problems, andlabor for transplanting the individual plants.

Aeroponic systems spray nutrient solution on the roots of plantsintermittently and have been used mostly in plant research. There areseveral styles of aeroponic units growing vegetables at Disney World inOrlando, Fla. However, modifications need to be made to existing systemsfor cost efficient commercialization.

SUMMARY OF THE INVENTION

Briefly stated, a system and method of aeroponic farming includesdepositing seeds in a flat containing micro-fleece cloth and placing theflat within a growth chamber. The upper side of the flat is subjected tolight of the proper frequencies to promote growth in plants. A nutrientsolution is sprayed onto the micro-fleece cloth and the developing rootmass of the plants, while controlling temperature, humidity, and carbondioxide within the growth chamber. The plants are harvested resultingfrom the seeds at a desired stage of growth. The growth chambers can bestacked on each other and/or located side by side to save space within afacility, and to permit sharing the subsystems which control thenutrient solution, temperature, humidity, and carbon dioxide for thegrowth chambers.

According to an embodiment of the invention, an aeroponic systemincludes a growth chamber; at least one flat effective for receivingseeds in an upper side thereof; light means for providing lighteffective for photosynthesis in plants; and means for spraying anutrient solution onto a lower side of the flats.

According to an embodiment of the invention, a method of aeroponicfarming includes the steps of (a) depositing seeds in at least one flatcontaining micro-fleece cloth; (b) positioning the at least one flatwithin a growth chamber; (c) subjecting an upper side of the at leastone flat to light of the proper frequencies to promote photosynthesis inplants; and (d) spraying a nutrient solution onto the micro-fleece clothand the developing root mass of the plants.

According to an embodiment of the invention, a cloth flat for seedgermination includes a plurality of strips of micro-fleece cloth sewntogether to form a plurality of transverse furrows that remain closedwhen tension is applied orthogonal to the furrows, whereby whenun-germinated seeds are positioned within the furrows, the closedfurrows protect the un-germinated seeds from direct light.

According to an embodiment of the invention, a structure for seedgermination and growth includes first and second sets of rails; whereineach set of rails includes an upper rail and a lower rail; first andsecond scissors mechanisms; micro-fleece cloth affixed between the firstand second scissors mechanisms; the first and second scissors mechanismsbeing contained within the first and second sets of rails, and, suchthat as the flat is moved along the first and second sets of rails, aconvergence of the upper and lower rails within each set of rails causesa length of the flat to be increased, while a divergence of the firstset of rails from the second set of rails causes a width of the flat tobe increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cloth flat according to an embodiment of the invention.

FIG. 2 shows a cross-section of a furrow in the cloth flat of FIG. 1.

FIG. 3 shows a cross-section of a furrow in the cloth flat in FIG. 1when the cloth flat is pulled taut.

FIG. 4A shows an alternate embodiment of a cloth flat.

FIG. 4B shows a detail of the embodiment of FIG. 4A.

FIG. 5 shows the cloth flat of FIG. 4A stretched in the lengthwisedirection.

FIG. 6A shows a partially cutaway view of an aeroponic module accordingto an embodiment of the invention.

FIG. 6B shows details of an embodiment of FIG. 6A.

FIG. 6C shows details of an alternate arrangement of moving the clothflats of FIG. 6A.

FIG. 7 shows an expanded view of a spray nozzle used in the embodimentof FIG. 6A.

FIG. 8 shows a partially cutaway side elevation view of the aeroponicmodule of FIG. 6A.

FIG. 9A shows a cross-sectional view of the aeroponic module of FIG. 8.

FIG. 9B shows an alternate embodiment of a grow lamp and ventilationduct used in the aeroponic module of FIG. 8.

FIG. 9C shows an alternate embodiment of a grow lamp and ventilationduct used in the aeroponic module of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Areas of controlled environment which are important to the design of afacility to allow successful growing of plants include the following.

Supplying light and maximizing its availability to plants in the rightwavelengths. Fluorescent, metal halide, and high-pressure sodium (HPS)are typically used for lighting and may be used to supplement sunlightor as the sole source of light. Metal halides supposedly supportvegetative growth better while HPS supposedly support flowering stagesbetter. The different lights have different life and attenuation times,so economic considerations for maintenance and replacement are required.Lights are extremely inefficient leading to excess heat production.Handling this heat production includes both air movement andwater-jacketing. As both the lights and the electricity becomesignificant input costs optimizing the space utilization under lights isimportant. The light (and nutritional) needs of plants duringgermination, growth, and flowering stages are different. Light needsvary among different species of plants. Many plants require a darkperiod diurnally for normal growth or a pre-harvest dark period forenhancement of plant characteristics including deleterious compounddissipation, enhanced flavor and color. Typical salad greens can begrown around the clock with little impact other than faster growth,while some evidence exists for a pre-harvest dark period to enhanceflavor, reduce nitrates, and improve color.

Optimizing space. Plants are arranged in ways that include vertical ornear vertical plant stacking, double cropping, and transplanting fromsmall allocations of space to larger as required by the plant growth.Trapezoidal modules with special features are arranged so that adjacentunits run in opposite directions. Modules can be stacked on each otherindefinitely, with changes needed only for introducing new plants andharvesting plants that have reached their desired stage of growth.

Providing best environment for roots. Light is not good for roots.Drying out of roots is the greatest danger to healthy plants. Also to beconsidered is the separation of the root and plant zones. Nutrients thatland on plant foliage may alter the taste and appearance of finalproduct. Nutrient excess from top spraying enhances algae growth andaids the spread of disease.

Preventing pests from damaging crops. Typical greenhouse use exposesplants to insects. Screening can be used to help with exclusion, andinsect predators are often used as a means of control. Pesticides are tobe avoided, but are still common in conventional outdoor or greenhouseproduction.

Reducing humidity. High humidity indirectly causes tip burn in leafycrops and causes a death of leaves at their perimeter, leading tounsightly foliage, especially post-harvest. The actual cause is believedto be a lack of sufficient calcium at the edges of the growing leafbecause of insufficient plant transpiration. By lowering the humidity,transpiration is increased and more calcium becomes available to thecells at the leaf edges. The total light per day also appears to be acontributing factor in causing tip burn, with heat and humidity makingtip burn worse. Tip burn is exhibited by a curling and browning (death)of cells at the edges of leaves. Further, plants create amicroenvironment in close proximity to the plant with an alteredatmosphere impacted by plant functions. This environment must bedisturbed to allow access to the enhanced atmosphere, typically lowerhumidity and increased CO2 concentration.

Maintaining proper temperature. Temperature management is important forboth germination and growth and varies among species of plant and duringstages of germination and growth. Most leafy greens are cold seasoncrops requiring temperatures below 70 degrees F. and more than 50degrees F. Methods used to reduce excess heat from the sun or lightingsystem (lights are inefficient sources of light and losses are in theform of heat) include cooling of (or from) the nutrient solution,shading, direct cooling of light bulbs via air or water (in a jacket)circulation, and mechanical or evaporative cooling of the plantatmosphere. Such methods need to be balanced with economics of energyuse and loss of atmospheric enhancements mentioned previously.

Providing labor efficiency. Any vegetable related process is typicallylabor intensive. Planting of leafy greens is generally automated in someway. Typically, the seeding is done in homogeneous beds to allow foruniformity in the seeding equipment. Labor is used where automatedharvesting has not proven satisfactory, such as where field conditionsand very small greens make this very difficult. Where the product has aproportion of diseased, malformed, or otherwise undesirable leaves,labor is required to clean the crop. Transplanting, usually for thinningpurposes, is labor intensive and poor handling can reduce subsequentcrop yields. If crops are dirty from dust in the field or from handlingand transportation, either the producer or the consumer must wash thegreens prior to consumption. Although washing has been automated, thereremains some labor in supporting the process.

Optimizing the atmospheric content and connection. An enhancement to theCO2 content in the growing area can save on both light requirements andincrease plant mass. This works against the humidity and temperaturecontrols because both are typically reduced by exhausting the atmosphereof the greenhouse or plant vessel. The plant/atmosphere connectionimpacts growth as a microclimate is established around each leaf, butdisturbing this climate is necessary to allow plants to benefit fromincreased CO2 and reduced humidity. Too much air movement near plantswill reduce growth and above 50 fpm will kill plants.

Optimizing nutrient usage. Nutrients in hydroponic systems are not usedup with one application. Most systems allow for the recirculation ofnutrient solutions for a finite period, with such a system known as aclosed system. Replenishment of nutrients into a recirculating solutionis also often practiced, with attention being paid to pH, EC (electricalconductivity), and contaminants (organic compounds from roots andorganisms growing in solution). Methods are often used to automateretention of proper solutions.

Referring to FIG. 1, a cloth flat 10 is shown. The use of cloth as agrowing medium allows for such cloth to be moved contrary to a cuttingtool, thereby providing automated harvesting of plants and roots. Thisis preferable due to uniformity of surface, ability to be bent overrollers, and lightweight and flexibility of material. Cloth of certainfibers is inert, does not become a biological substrate, and retainsattribute and function. It can be cleaned easily and reused for numerouscroppings. Organic fibers are to be avoided because they support plantpathogens and other undesirable organisms. Cotton is especiallysupportive of and possibly contributing foreign organisms to the medium.Non-organic fibers generally hold up under use better than organicfibers, but RAYON® deteriorates after 20 days of use.

The cloth should be unpilled on the upper side, i.e., the side with theseeds and leafy side of the plants. Algae grow better on surfaces withpill than on unpilled surfaces. The weight of the cloth is increasedwith pill on both sides of the cloth. No advantage is gained from theadditional expense of the cloth. The unpilled side does not supportgermination well, and depending on the looseness of the weave, does notallow root penetration, thereby causing plants to grow above or belowthe plane of the main cloth, or to push portions of the root above thecloth or the stem below the cloth, leading to less plant productivityand potential harvest losses.

Cloth proved to be a suitable medium but not all fabrics worksatisfactorily. Additionally, cloth allowed for space optimization, animportant consideration if using an all enclosed space. In many systems,plants must be handled (the reason for thinning in conventionalagriculture) when the plants begin to interfere with each other'sgrowth. Cloth as a growing medium is new, unique, and well suited to thepurpose of growing plants. It is especially useful for growingvegetables like salad greens by removing any chance for particulates tocontaminate the harvest, providing easy handling and automation ofcultural practices, and allowing cleaning for growing medium reuse.Further, cloth of the appropriate fiber and weave creates an optimalsimulation of proper growing conditions, including access to moistureand support for roots. Further still, cloth provides a barrier toseparate root and foliage zones, reducing or removing light from theroot zone and removing excess nutrient spray from the foliage zone.Cloth of appropriate weave, fiber, and thickness, and sewn inappropriate configurations can provide a proper germination space, allowplant root growth, provide plant support, and not inhibit unfurling ofcotyledons and subsequent leaves.

Soils, aggregates, and inert growth media (rock wool) can allcontaminate the final product with particles undesirable to the eater.Fabric that retains its fibers through out the growth of plants will notimpart anything to the harvested product. Cloth, by acting like aconveyer belt, lends itself to planting and harvesting. Cloth may bereused numerous times if plants are harvested and roots are removed.Further, this can be automated. Fabrics that allow root penetration andhold water without soaking seeds are able to grow healthy plants. Clothof the preferred type reduces light to the root zone and absorbsnutrients protecting the spray from reaching plant foliage.

Crops with tuberous roots that might cause plant foliage to be pulledinto the root zone may be maintained in place with a mesh attachedloosely as an additional layer to the original medium. Plants may beplanted in cloth where the fibers loosely hold the seed, protect it fromdirect light exposure, retain moisture without drowning, and allowinitial root hair stability to keep stem and root growing vertically.Experimentation has shown that rolled cloth inserted into slots of clothwith seed planted above the main cloth plane, seams where the pilledside is to the seed and extends above the seed, provide optimalconditions.

In summary, cloth is preferred because of its water absorbing andretention properties, its porosity allowing root growth, itsconstruction preventing spray from directly penetrating the cloth, itshandling properties facilitating space optimization, machine washing,seeding, and harvesting, its reusability, its ability to provide plantsupport, and its non-contamination of the harvested product.

Cloth flat 10 is preferably made of an artificial fiber such as amicro-fleece. The 100 weight POLARTEC® fleece, manufactured by MaldenMills Industries, Inc., 46 Stafford Street, Lawrence, Mass. 01842 undertheir product style 7365 was used with excellent results. POLARTEC®fleece is unpilled, and the 100 weight fleece is strong without beingtoo heavy. The wicking and water retention properties of themicro-fleece make it ideal for the system of aeroponic farming of thepresent invention. The 100 weight fleece has a weight of 10.0 oz. perlinear yard, 5.1 oz. per square yard, and 172 grams per square meter.

Cloth flat 10 is preferably constructed by cutting strips of fabric inthe lengthwise direction along the grain from a roll of fabric. As isstandard terminology, “lengthwise” is in the direction of the warp,while “crosswise” is in the direction of the weft. As shown in FIG. 1, afive inch strip 12 is sewn to a four inch strip 14. Strips 12 and 14 arepreferably fifty-seven inches long to allow an average person's arm spanto reach any spot on flat 10 from the edges. Another consideration inthe size of the flat was ensuring that the potential weight of the flat,including the weight of any harvestable plants and nutrients, issustainable by the material used. Strips 12 and 14 have a natural curlin the crosswise direction. Strips 12 and a plurality of strips 14 aresewn together along seams 18, leaving a plurality of transverse furrows20 formed from part of each strip. During sewing, the fabric of strips12 and 14 should not be stretched so as to preserve the natural curl ofthe fabric. In the embodiment shown, flat 10 includes eleven four-inchstrips 14 and one five-inch strip 12. A plurality of snaps 24 arepreferably attached to cloth flat 10 near the outer edges. The laststrip 14 includes a plurality of hook/loop patches 22 b, such as arecommonly known as VELCRO® which interconnect with correspondinghook/loop patches 22 a on strip 12 of an adjacent flat 10 (not shown).

The flat design is dependent on the desired plant spacing. An alternateembodiment has no furrows. A 12-hour period of covering after seedingwill provide sufficient moisture and protection from light to germinateseed. Although seeds aren't harmed by light, they must be moist all ofthe time but not sit in standing water. Experimentation has shown thatcloser plant spacing is better, with less algae, more product, andbetter water retention. In addition, the flats keep their shape betterwith closer seams. The length of the strips is determined by the machinewidth minus the trolley and rail width, minus a stretch factor which isdetermined by routine experimentation, i.e., a SWAG followed bysuccessive refinement.

As shown in FIG. 2, furrow 20 can be flattened open to permit placing aplurality of seeds 36 inside. When sufficient tension is applied to thesides of flat 10 as shown by double-headed arrow 16 (FIG. 1) to furrow20, furrow 20 closes, thus preventing seeds 36 from falling out of flat10. During the growing process, the shoots resulting from seeds 36 willpoke their leaves above furrow 20 to receive the light necessary forfurther growth. As the seeds sprout, the hairs of the radicals grip thecloth, while the roots penetrate the cloth. The plants maintain theirupright orientation without the need for cutting a hole or slot in thecloth.

An alternative to using furrows is to cover the micro-fleece cloth for24-48 hours to promote germination, because germination requireselevated moisture levels surrounding the seed. Once the seeds germinate,the cover is carefully removed so as not to disturb the hairs of theradicals which are gripping the micro-fleece cloth.

Referring to FIG. 4A, a flat 40 according to an alternate embodiment ofthe invention is shown. Flat 40 includes a plurality of dimensionalpuckers 48 to gather excess fabric. Rings 50, plastic or metal, thatrelease the fabric as it is stretched, hold the fabric in thesedimensional puckers 48. Small pieces of cloth are used to germinate theseeds, thereby removing the need for a special germination facility.These small pieces of cloth are termed growth puckers 52 and remain withthe plant through harvest. Growth puckers 52 hold the seeds, whiledimensional puckers 48 gather up the loose fabric. RAYON® is preferredfor the growth puckers 52 because it deteriorates before harvest.

The fabric of flat 40 is attached to a scissors mechanism 42 on eachside via rods 62 which fit through sleeves 64 in flat 40. A scissorsmechanism 42 includes a plurality of upper wheels 44 and a correspondingplurality of lower wheels 46 which fit into separate upper and lowerright and left pairs of rails (not shown). A height 56 (measured fromthe centers of the corresponding pairs of upper and lower wheels 44, 46)is controlled by the distance between each pair of upper and lowerrails. As each upper rail moves closer to its corresponding lower rail,causing height 56 to diminish, a length 58 of flat 40 increases. Thus,length 58 is controlled by controlling the spacing between the upper andlower rails. A width 60 of flat 40 is controlled by the spacing betweenone pair of upper and lower rails (not shown) and the other pair ofupper and lower rails (not shown). As shown in FIG. 4B, rods 62 expandand contract as necessary to permit scissors mechanism 42 to stay withinthe pairs of rails (not shown). A plurality of buttons 66 in flat 40 areretained in a plurality of guide tracks 68 to keep the cloth in flat 40evenly stretched within scissors mechanism 42. Without such buttons, thecloth could easily stretch succeeding dimensional puckers 48 instead ofall dimensional puckers 48 equally, thus exceeding the needs of someplants 54 while not meeting the needs of others.

Referring to FIG. 5, as plants 54 in flat 40 grow larger, more space isrequired on flat 40. Reducing height 56 to a height 56′ increases thelength 58′ of flat 40. Width 60′ can be adjusted as described above.Dimensional puckers 48 reduce themselves as the dimensions of flat 40increase, eventually disappearing. Rings 50 pop off of dimensionalpuckers 48 and can be recovered for reuse. Dimensional puckers shouldnot be placed below the plane of the fabric, as doing so allows rootpenetration and subsequent ripping of roots as the material is drawnfrom the pucker. The placement of the pairs of rails within an aeroponicmodule is dependent upon the plants being grown, the plants' growthrate, and the plants' eventual size.

Referring to FIGS. 6A-9C, a growth chamber 5 includes at least oneaeroponic module 70. Note that module 70 is designed for flats 10 andlacks the dual rails required when using flats 40, but otherwise issimilar. Flats 10 are used when the plants are not grown to full size,as for example, when growing baby greens of lettuce, arugula, spinach,etc. A series of modules 70 can be placed end to end to extend the totallength of growth chamber 5. Depending on space, modules 70 and series ofmodules 70 can be stacked on one another, i.e., forming one growthchamber 5 over another growth chamber 5, such as is shown in FIG. 9A asmodule 104. A roof 102 (FIG. 9A) of each growth chamber 5 is preferablyreflective and insulating, for example, made of TEKFOIL® availablethrough Farmtek, 1395 John Fitch Blvd., South Windsor, Conn. 06074,while a floor of each growth chamber 5 is preferably of high molecularweight polyethylene (HMWPE), which is strong, can be welded, and can beshaped to form a trough. The purpose of the growth chamber is to enablemanagement of chamber temperature, humidity, and carbon dioxide; forsmaller systems, such management is preferably done within a module 70or series of modules 70. There is no theoretical limitation on the sizeof the growth chamber, and in fact, an entire building or warehousecould be used as one large growth chamber.

As shown in FIG. 6B, flat 10 is fastened via snaps 24 to correspondingsnap studs 26 in trolleys 28, 30 which in turn fit inside slots 106 introlley rails 32, 34 respectively. Snap studs 26 are spaced apart theproper distance to support flat 10. Successive sets of trolleys arepreferably connected to each other via a small metal ring 118 or otherfastener. Trolleys 28, 30 and trolley rails 32, 34 are of a strongnon-rusting material such as plastic or preferably aluminum. Trolleys28, 30 are preferably interconnected with slots 106 by small wheels 116which prevent trolleys 28, 30 from falling out of trolley rails 32, 24as well as permitting flat 10 to be advanced along trolley rails 32, 34when pulled by a rope 86 (FIG. 6A) or ropes 86′ (FIG. 6C). Trolleys 28,30 could be automated and advanced along trolley rails 32, 34 by a chainwithin trolley rails 32, 34 or rope 86 could be connected to a motor andgears which would advance flat 10 along trolley rails 32, 34. Suchautomation, including computerized or mechanical controls for such, isconsidered to be within the ordinary competence of one skilled in theart, so further description is omitted here.

Referring to FIG. 6C, an embodiment is shown in which snap studs 26 areattached directly to a rope 86′, thus obviating the need for trolleys28, 30. A crank 120 pulls rope 86′ across a pulley 122, thus movingflats 10 which are snapped to snaps 26. FIG. 6C shows a right hand rope86′ and pulley 122; a similar setup is on the left hand side of growthchamber 5, preferably with an axle 124 of pulley 122 extending to theleft hand side pulley (not shown). Thus, cranking crank 120 moves flats10 evenly through growth chamber 5. As flats 10 reach the location ofpulley 122, an automated cutting apparatus (not shown) could cut theplants, with the cut plants dropping down into a collection chute (notshown), which in turn could lead to a bagging apparatus (not shown) forbagging the produce in a market-ready container.

The speed of advancement would depend on the growth rate of the plantsbeing grown in flats 10 and could be a very slow continuous advancementor a periodic advancement. In practice, as long as the series of modulesis not so long that a person cannot advance multiple flats 10 simply bypulling on rope 86 or ropes 86′, manual pulling of rope 86 or crankingof ropes 86′ using crank 120 is preferred for small systems. Rope 86 canbe directly attached to the leading flat 10, to the leading edge of theleading trolleys 28, 30 directly or by a bridle arrangement, or to awooden or metal dowel which is fastened to the leading edge of trolleys28, 30.

Referring back to FIG. 6A, trolley rails 32, 34 are supported by theframework composed by a plurality of framing members 76, as are aplurality of side panels 72. Framing members 76 are preferably of amaterial such as angle iron dimensioned to support side panels 72 androof panel 102. Side panels 72 and the roof panel are of a suitablematerial such as preferably TEKFOIL®. An end panel (not shown) ispreferably hinged at the top to permit easy access to the end ofaeroponic module 70.

A plurality of tubes 80 are preferably connected in a framework toprovide support for flats 10 as they become weighted down by moisture orgrowing plants. Tubes 80 are preferably of PVC, but can be of anyrust-proof material that is strong enough to support the weight of flats10 when they are fully loaded with plants. A plurality of tubes 82,preferably of PVC, are used to transport a nutrient solution from anutrient tank 92 (FIG. 8) as pumped by a nutrient pumping system 94 to aplurality of spray nozzles 84 which spray a nutrient spray 98 (FIG. 7)onto the bottom of flats 10, where the nutrient solution provides thenecessary nutrients to the growing plants. Excess nutrient solutionpreferably drips down onto a nutrient return tray 90 (FIGS. 8, 9A) whichpreferably returns the nutrient solution to nutrient tank 92 for re-use.Nutrient return tray 90 is preferably a sheet of plastic, e.g., HMWPE orFRP, connected to horizontal framing members 76 which parallel trolleyrails 32, 34. A cross-section of nutrient return tray 90 is preferablyarcuate in shape. Although a closed system is preferable and describedherein, the present invention can optionally be implemented withoutre-using the excess nutrient solution.

Spray nozzles 84 preferably provide a wide spray pattern and include ascreen, such as the CC-213 providing 3 GPH@ 100 PSI in a 115 degreespray angle manufactured by KES Industries and available from EcologicTechnologies, P.O. Box 1038, Pasadena, Md. 21123. Nutrient pumpingsystem 94 (FIG. 8) preferably includes a booster pump available fromW.W. Grainger, Inc., 100 Grainger Parkway, Lake Forest, Ill., 60045model #2PC20-1 driven by a variable frequency drive manufactured byEetron, P.O. Box 4645, Ithaca, N.Y. 14850 connected to a pressuresensor. The pump receives nutrient solution from a large reservoir.Smaller systems can use a diaphragm pump (6 GPM @ 60 PSI), a pressuretank to relieve the pump of constant running, and a large capacity (25GPM) filter with a 50 micron pore size insert to remove anything thatmight clog the nozzle screen. The pump capacity is arrived at by meetingthe total capacity of the misting nozzles (nozzles 84), calculating 1GPH per nozzle times 360 nozzles equals 6 GPM, although some slack isrecovered by using the pressure tank Such filters are available as partnumber 44075K611 from McMaster-Carr of Aurora, Ohio. A timer, alsoavailable through Ecologic Technologies, is preferably part ofelectrical control panel 96 to manage the timing, duration, and intervalof the spray.

Side panels 72 are preferably lined with a lining 74 to increasereflectivity of light 100 produced by a plurality of grow lamps 88preferably inside a duct 112 with a window 114 under each grow lamp 88.In general, a grow lamp is any lamp, light, or series of lights, ormechanism for piping light in from outside the growth chamber, ormechanism for piping sunlight into the growth chamber, as long as thelight is effective to promote photosynthesis in plants. Lining 74 ispreferably of MYLAR® film manufactured by DuPont. A plurality of fans 78provide air circulation within module 70, while a separate air movementsystem for the entire growth chamber 5, irrespective of the number ofmodules 70, includes an air intake 108, duct 112, an air exhaust 110,and a fan (not shown) for the air movement within duct 112 controlled byan electrical control panel 96.

There are three air circulation needs: (a) turbulence is needed tomaintain good contact between the plants and the atmosphere, in therange of from 20 to 50 FPM, (b) a chamber exhaust is needed for removingair that is either too high in temperature or too high in humidity,preferably specified to exhaust the entire volume of growth chamber 5within about three minutes (as determined by routine experimentation),and (c) excess heat must be removed from grow lamps 88, because growlamps 88 are only about 30% light efficient. Fans 78 are preferablyplaced every 10 feet instead of using one large one to keep the FPM lowand yet ensure all plants 54 receive a breeze. Air conditioning isoptionally used for the influent for the chambers but not for the lightduct. The exhaust and light fans are centralized drawing from a plenumfiltered by thrips level screen. (Thrips are very small, slender insectsthat are on the order of 0.05 inch (1.3 mm) to 0.06 inch (1.5 mm) long.)

Referring to FIGS. 8, 9B, and 9C, grow lamps 88 are typically specifiedbased on the area to be covered at a minimum light level. Grow lamps 88are preferably spaced every five feet. Reflectors 89 are preferable asthey both increase light available and manage the pattern. The finalconfiguration of the working module 70 uses a 400-watt HPS ballast andbulb with an EconoGro reflector mounted in duct 112 with tempered glassor other window 114 covering a hole in duct 112 that allows light 100 toshine on flats 10. The lighting systems are available from CropKing,5050 Greenwich Rd., Seville, Ohio. In FIG. 8, reflector 89 is mountedwithin duct 112 between the upper and lower sides of duct 112. In FIG.9B, reflector 89 is mounted to the upper side of duct 112, while in FIG.9C, reflector 89 is mounted on the lower side of duct 112. These threedifferent mounting locations cause the air flow within duct 112 to movepast different parts of the reflector 89 and grow lamp 88 combination.Grow lamps 88 are optionally controlled by a controller (not shown)which controls the intensity, timing, number of lamps or any combinationof these variables. Implementing such a controller is considered to bewithin the ordinary competence of one skilled in the art, so furtherdescription is omitted here. It is preferred to provide even lightintensity to the growing plants to equal 15-20 moles/meter/day.

Carbon dioxide is optionally controlled by introducing CO2 from a tank.CO2 is easily delivered to and distributed within the chamber. Plantsmay deplete the CO2 to levels far below normal ambient (ambient istypically 400 ppm±50 ppm), requiring supplementation. Elevated CO2 hasbeen shown to accelerate plant growth.

Care must be taken not to expose the foliage zone to the root zoneeither through loss of cloth integrity or around the ends of one or aseries of flats 10 not filling module 70. Algae growth becomes markedlyenhanced, using up nutrients, creating a thicker layer interfering withclean harvesting, and making the growing area unsightly. Plant leavesoften become dusted with dried nutrients, interfering withphotosynthesis, potentially altering flavor, and making the productappearance less clean and bright. For this reason, two-inch strip 14(FIG. 1) of flat 10 is designed to overlap a trailing flat 10 withinmodule 70. The flats must overlap completely to avoid spray to the topof the flats and light to the bottom, which causes increased algaegrowth. For the same reason, stretch should not cause large gaps betweenthe edge of the flats and the trolley between the snaps.

Various system considerations follow. The nutrient solution is sprayedfrom underneath flats 10. Irrigation is preferably in ten foot zones,matching the size of the individual modules. The size of the individualmodules is mostly a function of the readily available lengths of thematerials used, such as PVC, RFP, aluminum, angle iron, etc. Lengtheningthe interval of nutrient spraying creates root damage, while increasingthe intensity of the spray removes root hairs. Loss of electricitycreates plant death in less than three hours depending on relativehumidity, temperature, and size of plant. Placing lights in a duct withtempered air circulation both cools the lamps and removes heat fromplant areas. Heat may be recovered for other purposes. The duct may beplaced above plants in such manner as to control and alter the distancefrom plant to lamp as required by stage of growth. Using a tightenclosure with filtered air reduces the risk of insect infestation.Moving the plants, while growing, through the chamber averages theimpact of placement relative to the light pattern, asynchronous changesin the light intensity of different lights as they age, nutrient spraypattern, local atmosphere, or cloth moisture, thereby ensuring a uniformcrop. Lights present a varying pattern of light quantity and qualityimpacted by bulb orientation and construction, reflector, and any lens(thickness, color, and material) placed between the plants and light.Plants are impacted by reflectance and absorbance of materials of thewalls or suspended in the growth chamber. Nutrients provided via nozzleswhich create fine mists may direct droplets in varying degrees to anyone place in the spray pattern. The local atmosphere may vary because offan placement and proximity to chamber walls. Cloth will puddle thenutrient solution slightly if it dimples due to insufficient tension oranomalies in the cloth and/or flat fabrication. Seeds placed in suchpuddled areas germinate and grow differently, some better and some worsethan others.

The technology provides the following advantages. The use of cloth,fabrication of flats made of cloth, and the method of spacing plants arenovel. Optimization and automation of plant spacing avoids labor and thetrauma to plants. It also removes wasted space, including related costsof light, nutrients, and other inputs, that some other types ofhydroponics must employ. The mobility of cloth flats also lends itselfto a variety of labor saving designs for planting, harvest, andpackaging. The use of cloth for a growth medium is potentially lessexpensive than rock wool. The green aspects of the technology includeminimal use of water per plant due to spacing and enclosure, littleeffluent created as solutions are recycled, reuse of the cloth growthmedium, and maximum energy efficiency. Further improvements could begained from alternative power sources, use of excess heat, andgeneration of compost or animal feed from any discarded plant material.Lamp heat is removed and is available for use beneficially to heatexternal space, and the light intensity to the plants is controlled.Plant growth is supported. Space is optimized relative to the plantstage. The root and foliage zones of growing plants are separated.Plants are protected from insect infestation. Crop uniformity isimproved. The invention lends itself to automate harvests. The plantgrowth medium is reusable.

The growth chambers can be built with one unit or with more than tenunits, since each chamber is self-contained with low external impact.This flexibility in construction of the growth chambers allowsconventional warehouse space to be used. The use of multiple chambersallows tailoring of each chamber to the specific needs of the plantsbeing grown including light, temperature, nutrient composition,delivery, and space. There is little waste of the CO2 used inatmospheric enrichment. Light usage is maximized. Redundancy throughmultiple chambers in a facility reduces the risks of crop failures,especially when compared to conventional farming or greenhouse farming.

Table 1 compares the characteristics of conventional field grownproduction with production from the present invention. TABLE 1Characteristics Conventional Present Invention When available Onlyduring summer Grow every day Growth efficiency Harvest on day 35-70Harvest before day 20-25 Space efficiency Rows 24″ apart Plant dependentspace Energy efficiency From 10 to 30 trips across Only optimizedelectrical field; trucking; washing applications Safety Pesticides Nopesticides Labor efficiency Hours of menial labor Minutes of laborCapital efficiency Variable yield and cost Predictable yield and costWater efficiency Typically irrigated Recycled nutrient solutionDistribution from 1-10 days Fresh locally today efficiency truckingShelf life at 1-4 days 10-21 days destination

In operation, flat 10 is wetted with nutrient solution, after which theseeds are added. When using flats with furrows, furrows 20 are flattenedout. Seeds 36 are placed in each furrow 20 a suitable distance apart.Tension is applied to flat 10 to close the furrows 20. Flat 10 issnapped to trolleys 28, 30 before being carried to module 70, whichenhances keeping flat 10 under tension. Flat 10 is then carried andplaced inside aeroponic module 70, where flat 10 is snapped to trolleys28, 30. Flat 10 is now within the growth chamber. Alternately, flat 10is placed within the growth chamber before seeds 36 are “planted” withinfurrows 20. A number of “planted” flats 10 can be placed within module70, depending on the number of plants and days of growth desired. Asgermination proceeds, additional flats 10 can be prepared with seeds andplaced inside the growth chamber. The leading flat 10 is moved asdescribed earlier, and the connection of chains of trolleys 28, 30 movesall flats 10 into the growth chamber. The flats 10 are moved withingrowth chamber 5 such that when the leading flat 10 reaches the end ofthe growth chamber, plants 54 are ready for harvesting. The length ofthe growing operation depends on whether baby greens or full plants arebeing grown.

While the present invention has been described with reference to aparticular preferred embodiment and the accompanying drawings, it willbe understood by those skilled in the art that the invention is notlimited to the preferred embodiment and that various modifications andthe like could be made thereto without departing from the scope of theinvention as defined in the following claims.

1. An aeroponic system, comprising: a growth chamber; at least one flateffective for receiving seeds in an upper side thereof; light means forproviding light effective for photosynthesis in plants; and means forspraying a nutrient solution onto a lower side of the flats.
 2. A systemaccording to claim 1, further comprising: means for circulating airthrough the growth chamber; and means for collecting excess nutrientsolution for reuse.
 3. A system according to claim 2, further comprisingmeans for recirculating the collected excess nutrient solution to themeans for spraying.
 4. A system according to claim 2, further comprisingmeans for controlling the humidity and heat of the atmosphere within thegrowth chamber.
 5. A system according to claim 4, further comprisingmeans for controlling the level of carbon dioxide within the growthchamber.
 6. A system according to claim 2, further comprising means forcirculating air over the light means to provide an air-cooled lightingsystem, and wherein the means for circulating air through the chamber isindependent from the means for circulating air over the light means. 7.A system according to claim 1, wherein the flat includes micro-fleececloth.
 8. A system according to claim 7, wherein the micro-fleece clothincludes a plurality of transverse furrows that remain closed whentension is applied orthogonal to the furrows, whereby when un-germinatedseeds are positioned within the furrows, the closed furrows retainmoisture in close proximity to the un-germinated seeds.
 9. A systemaccording to claim 1, further comprising a plurality of growth chambersadjacent each other sharing a common boundary.
 10. A system according toclaim 1, further comprising means for adjusting a distance between thelight means and the at least one flat.
 11. A system according to claim1, further comprising means for automatically moving the at least oneflat through the growth chamber.
 12. A system according to claim 11,wherein the growth chamber includes a plurality of zones, and the systemfurther comprises: means for independently adjusting an amount of growthlight within each zone; and means for independently adjusting an amountof nutrient solution sprayed within each zone.
 13. A system according toclaim 11, further comprising means for automatically seeding the atleast one flat with seeds, and means for automatically harvestingresulting plants from the at least one flat.
 14. A system according toclaim 11, wherein the at least one flat includes first and second flats,the system further comprising means for connecting the first and secondflats together such that nutrient solution sprayed onto the lower sideof the flats does not enter a part of the growth chamber that is betweenthe flats and a top side of the growth chamber.
 15. A system accordingto claim 1, further comprising means for circulating air through thegrowth chamber, and means for filtering air from insects when the air isreceived from outside the growth chamber.
 16. A system according toclaim 1, further comprising means for reflecting light within the growthchamber.
 17. A method of aeroponic farming, comprising the steps of:depositing seeds in at least one flat containing micro-fleece cloth;positioning the at least one flat within a growth chamber; subjecting anupper side of the at least one flat to light of the proper frequenciesto promote photosynthesis in plants; and spraying a nutrient solutiononto the micro-fleece cloth and the developing root mass of the plants.18. A method according to claim 17, further comprising the steps ofcontrolling temperature and humidity within the growth chamber, andharvesting the plants resulting from the seeds at a desired stage ofgrowth.
 19. A method according to claim 18, further comprising the stepof controlling the carbon dioxide level within the growth chamber.
 20. Amethod according to claim 17, wherein the at least one flat includesfurrows formed in the micro-fleece cloth.
 21. A method according toclaim 17, further comprising the step of covering the deposited seeds toimmerse the seeds in a moist environment for a time period sufficientfor the seeds to germinate.
 22. A method according to claim 21, whereinthe step of covering the seeds includes depositing the seeds in aplurality of transverse furrows in the micro-fleece cloth.
 23. A methodaccording to claim 22, further comprising the step of applying tensionto the micro-fleece cloth applied orthogonal to the furrows to close thefurrows to immerse the un-germinated seeds in a moist environment.
 24. Amethod according to claim 17, further comprising the step of adjusting adistance between the light and the at least one flat.
 25. A methodaccording to claim 17, further comprising the step of automaticallymoving the at least one flat through the growth chamber.
 26. A methodaccording to claim 17, wherein the growth chamber includes a pluralityof zones, and the method further comprises the steps of: independentlyadjusting an amount of growth light within each zone; and independentlyadjusting an amount of nutrient solution sprayed within each zone.
 27. Amethod according to claim 17, further comprising the steps ofautomatically seeding the at least one flat with seeds, andautomatically harvesting resulting plants from the at least one flat.28. A method according to claim 17, wherein the at least one flatincludes first and second flats, the method further comprising the stepof connecting the first and second flats together such that nutrientsolution sprayed onto the lower side of the flats does not enter a partof the growth chamber that is between the flats and a top side of thegrowth chamber.
 29. A method according to claim 17, further comprisingthe steps of circulating air through the growth chamber, and filteringair from insects when the air is received from outside the growthchamber.
 30. A method according to claim 17, further comprising the stepof reflecting light within the growth chamber.
 31. A cloth flat for seedgermination, comprising a plurality of strips of micro-fleece cloth sewntogether to form a plurality of transverse furrows that remain closedwhen tension is applied orthogonal to the furrows, whereby whenun-germinated seeds are positioned within the furrows, the closedfurrows protect the un-germinated seeds from direct light.
 32. Astructure for seed germination and growth, comprising: first and secondsets of rails; wherein each set of rails includes an upper rail and alower rail; first and second scissors mechanisms; cloth affixed betweenthe first and second scissors mechanisms; the first and second scissorsmechanisms being contained within the first and second sets of rails,and, such that as the flat is moved along the first and second sets ofrails, a convergence of the upper and lower rails within each set ofrails causes a length of the flat to be increased, while a divergence ofthe first set of rails from the second set of rails causes a width ofthe flat to be increased.
 33. A structure according to claim 32, furthercomprising means for retaining an even dispersion of seeded plants asthe plants grow in the cloth as the cloth is moved along the first andsecond sets of rails.
 34. A structure according to claim 33, furthercomprising means for retaining excess cloth until required.